1. Field of the Invention
The present invention relates to an image recording apparatus and method, and in particular to a technique which can be employed to record a moving image signal of a high speed frame rate in response to an instruction for switching a frame rate while recording a moving image signal of a standard frame rate.
2. Description of the Related Art
In general, an image sensor is used for a video camera. For example, a charge-coupled device (CCD) sensor is used. Alternatively, a complementary metal-oxide semiconductor (CMOS) sensor is also used. Recently, it is possible to drive these image sensors at a high speed, so that a video image is read at a high speed frame rate in comparison with a standard rate and recorded in a recording medium so that a slow video image can be reproduced with a smooth motion.
In a moving image of a high speed frame rate, a data amount in a recording time increases in comparison with a standard rate, so that a recordable time relative to recording medium capacity is reduced. On the other hand, in the case of maintaining a length of the recording time, a data amount per frame is reduced, accordingly, the image quality of the recorded moving image is degraded. Therefore, when a moving image is captured, a user may want to record only a specific scene during the shooting at a high-speed frame rate.
Japanese Patent Application Laid-open No. 2004-242267 describes a technique of generating from input moving image data, a moving image for normal reproduction, and generating a moving image for slow reproduction only at a predetermined section of the moving image. In addition, Japanese Patent Application Laid-open No. 2001-036848 describes the following technique. A moving image for slow reproduction read out at a high-speed frame rate from an image sensor is recorded in a hard disk drive (HDD) at a high speed. At the same time, a moving image for normal reproduction as to the same scene is recorded in a digital video cassette (DVC). Then, a slow video image is obtained by sequentially reading the moving images at a normal speed which is recorded in the HDD at a high speed.
On the other hand, a digital versatile disc (DVD) has been increasingly used as a recording medium for recording a moving image and a voice captured by a video camera. Many of these video cameras encode the captured moving image and voice with codec of Moving Picture Experts Group (MPEG). Then, the video camera records the encoded data as video data corresponding to a “DVD-Video” (hereinafter, referred to as “VIDEO”) format or a “DVD Video Recording” (hereinafter, referred to as “VR”) format. In addition, recently, an HDD or a Blu-ray disc (BD) is employed as a recording medium other than the DVC or DVD in a video camera.
However, when a function of the high speed frame rate described above is performed using such a video camera, a moving image for normal reproduction and a moving image for slow reproduction are simultaneously generated according to the technique described in Japanese Patent Application Laid-open No. 2004-242267, thus imposing large load on an apparatus and incurring high cost.
In addition, according to the technique described in Japanese Patent Application Laid-open No. 2001-036848, two recording mediums are retained in order to record both of a moving image for normal reproduction and a moving image for slow reproduction, thus resulting in high cost.
Further, in the case of a video camera in which a DVD or the like is used as a recording medium, compatibility is important. For example, there is a possibility that a DVD in which encoded image data has been recorded by the video camera is set at other reproduction apparatus. In such a case, a video camera needs to carry out data recording in a mode considering compatibility so that another reproduction apparatus normally recognizes the inserted DVD and continuously reproduces image data based on a plurality of the recorded frame rates. However, the techniques of Japanese Patent Application Laid-open Nos. 2004-242267 and 2001-036848 do not consider the compatibility about a recording medium or recording data.